Batwoman Brings Back a Major Arrowverse Weapon in "A Secret Kept From All the Rest"

Batwoman's first season is winding down and with one episode remaining, the complicated relationship between Kate Kane/Batwoman (Ruby Rose) Alice (Rachel Skarsten) is coming to a head in a major way. After a season of trying to exact revenge on her family for what she perceives as them giving up on her after she was believed to be dead in a horrific accident as a child and, then, trying to win her sister Kate over to her side, Alice has finally settled on a different conclusion to her story: kill Batwoman. Tonight's penultimate Season 1 episode, however, throws a major twist into the situation -- one that leaves some major questions to be explored.

Spoiler's for Sunday night's episode of Batwoman, "A Secret Kept From All the Rest", below.

This week's episode continued the mystery of Lucius Fox's journal. Last week's episode saw the important tome acquired by Batwoman after great effort only to be stolen again, this time by Kate's love interest, Reagan, who ended up being Magpie's sister. The journal then made its way into Alice's hands which is where the complications begin. The journal, which is said to contain detailed information critical to Batman including weapons and other details, is written in an intricate code, prompting Alice, Mouse (Sam Littlefield), and Hush (Gabriel Mann) to find someone to break it.

By the end of the hour, the code is broken by Luke (Camrus Johnson) but a pair of glasses that his father left behind ends up making the journal easily readable for whoever wears them. Batwoman trades those glasses to Alice for Luke and Julia's (Christina Wolfe) lives despite knowing that whatever is in that book just so happens to be the secret of how to kill her. That secret? in the episode's final moments it's revealed that the key to killing Batwoman is kryptonite.

The idea that kryptonite is the key to killing Batwoman is an interesting and huge twist. As DC fans know, kryptonite is traditionally a weakness of Superman and Supergirl. On The CW's Supergirl, we've seen in Arrowverse canon just how dangerous the substance can be to the Kryptonian heroine. The danger that kryptonite poses to Supergirl is something that was even directly highlighted during "Crisis on Infinite Earths" when Supergirl/Kara Danvers learned that Batwoman/Kate had a piece of it.

As a method for killing Batwoman, however, things get a little confusing. As a human being, Kate isn't likely to be poisoned by kryptonite the way a Kryptonian would. Instead, long-term exposure to the substance would, eventually lead to cancer in a human and Alice isn't really playing that lengthy of a long game. The most obvious mechanism by which kryptonite could be a real threat to Batwoman is that it's a needed part of a much larger whole -- perhaps as a way to recreate the Batsuit-piercing gun first seen in the episode "Tell Me the Truth". In that episode, Alice and Mouse ensure that all of the scientists who could recreate the specific weapon -- one that The Rifle was attempting to obtain -- are dead so that Batwoman cannot be killed.

And there are clues that the kryptonite is needed for weapons purposes. The episode also reveals that Julia has been working for Safiyah, the person who first sent The Rifle to Gotham to kill Batwoman in the first place. Julia had made a deal with Safiyah to get the journal for her, unaware that it contained details on how to kill Batwoman. If Safiyah wanted the journal to find another way to kill Gotham's hero, it seems like pretty solid evidence that kryptonite is the key to some sort of batkiller, and it's something that series showrunner Caroline Dries hinted ties things back into things introduced in "Crisis".

"That idea came from me feeling like -- I just didn't want the next weapon we talk about to be something that was manmade, that if somebody put their heads together, they could maybe go into a lab and cook up," Dries said. "So, what exists in the world that is unique enough, that there'd be a very limited amount that makes it special? The idea of Kryptonite popped in my brain, and it made perfect sense to me, that this sort of talisman exchange between Kara and Kate in the crossover was just so much more than just a rock. It, to me, represents their bond and their friendship and that sense of trust between them. And I kind of like anchoring the chaos of all of the Arrowverse and all of what happened in 'Crisis' to this friendship."


"And what do you know? It's the one thing that can actually kill Batwoman, if used right," she continued. "So, while it sort of felt like, 'Are we going sci-fi? Is this weird? Is this cross-genre? Are we getting too big?'
It really felt like, 'No, it makes sense.' It introduces it in the show, and we want to say that 'Crisis' happened and it is still part of our world, even though we don't have aliens flying around every episode."

Batwoman airs Sundays at 8/7c on The CW.